Problem: $-\dfrac{6}{3} + \dfrac{9}{5} = {?}$
Explanation: $ = - {\dfrac{6 \times 5}{3 \times 5}} + {\dfrac{9 \times 3}{5 \times 3}} $ $ = - {\dfrac{30}{15}} + {\dfrac{27}{15}} $ $ = - \dfrac{{30} + {27}}{15} $ $ = -\dfrac{3}{15}$